The present invention relates to a method and apparatus for exposing transparent masters onto light sensitive material in the form of individual sheets. Each sheet is positioned with respect to the exposure field in an image plane of an optical projection device such that the optical axis of the projection device passes next to the center of the sheet.
Both professional and amateur photographers have increasingly felt the need to print enlargements of only details of the original negatives or diapositives (masters). Another increasingly frequent demand is for the ability to print index prints, which are sheets of miniatures of all or several of the masters on one film. Index prints have in the past been contact printed onto black-and-white paper in the photographic laboratory. They are useful for filing and as proofs that allow customers to select final photographs for purchase. Contact prints, however, are not made available by many laboratories because they require a lot of expensive labor.
Some recent printers intended for professional photographers include film supports mounted on an X-Y carriages. These carriages, however, are very complicated and expensive and cannot be employed in high-output printers wherein several rolls of film are fastened end-to-end into a strip that travels through the printing station. Since the films in this type of printer are wound off a reel upstream of the printing point and wound onto another one downstream of that point, it is practically impossible to displace the strip in a direction transverse to the direction it travels in.
The German Patent Publication No. OS 3,343,336, in FIG. 8, discloses a device for positioning a light-sensitive individual sheet with respect to the exposure field in an image plane of an optical projection device such that a plurality of images on a photographic film can be successively exposed in this sheet. However, this device uses an X-Y carriage which is both complicated and expensive.